make a deal with them IN WRITING pay the whole amount $20.00 a month if they promise to remove it when paid off. make payments without fail and if/when you have more cash pay it all off, Get a second job to expedite this. BUT only if and when they put it in written form
as for your amazement you owed money? Yes insurance is insurance not free medical care.
good insurance always has a deductible of some kind a amount each year .. the higher the deductible the lower you pay in premiums and it is most likely you choose the cheapest you could find,..,.. if someone else is pay the premiums parent, employer, tax payers you need to realize what you signed up for.... $900.00 is very cheap to get away with for a emergency room visit
as well make sure you learn what is covered and what it not.. too many people walk around pretending they have it all covered then go for like a TMJ surgery and find out the doctor lied about it being covered ... many many things are not covered
you learned a cheap lesson .. it could have been $50,000.00